Drive assistance device

ABSTRACT

Provided is a drive assistance device for a self-driving car with which drive assistance is less liable to be deactivated, even if an abnormality of a monitoring device for monitoring a state of a driver occurs. A device checking ECU checks whether a plurality of monitoring devices for monitoring the state of the driver are normal or abnormal. On the basis of the check result, an assistance degree determination unit (function availability determination unit) determines a use degree (availability) of a plurality of drive assistance functions (ACC function, LKAS function, and ALC function) including an ACC function. Drive assistance effected by a vehicle with respect to the driver is therefore less liable to be deactivated.

TECHNICAL FIELD

The present invention relates to a driving assistance device (driveassistance device) that is suitably applied to a vehicle having drivingassistance functions that assist a driver in driving the vehicle, suchas an inter-vehicle distance control function, a lane keeping function,and an automated lane change function, for example.

BACKGROUND ART

In recent years, an automated driving vehicle including a plurality offunction devices that assist a driver in driving the vehicle has beensuggested.

For example, Japanese Laid-Open Patent Publication No. 2007-168720discloses a technique where, in an automated driving vehicle thatreduces a burden of a driver in driving, a steering assistance processis prohibited when it is recognized that steering torque by the driverwho grips a steering part has decreased, that is, driving intention ofthe driver has decreased (in the paragraphs [0059], [0062] in JapaneseLaid-Open Patent Publication No. 2007-168720).

SUMMARY OF INVENTION

In such an automated driving vehicle, a prerequisite of the drivingassistance is that a driver is in what is called the driver-in-the-loopstate (where the driver monitors the periphery) as a result ofmonitoring the state of the driver in the vehicle.

In this case, it is preferable that the monitoring of the state of thedriver is performed using a plurality of monitoring devices from theviewpoint of improving certainty of the monitoring.

However, in a case where one monitoring device among the monitoringdevices becomes abnormal, if an automated driving control devicedetermines that it cannot be recognized that the driver is in thedriver-in-the-loop, all the function devices are disabled and thedriving assistance is cancelled. In this case, the convenience and themerchantability are decreased drastically.

The present invention has been made in view of such a problem, and anobject is to provide a driving assistance device for an automateddriving vehicle in which driving assistance is cancelled less easilyeven if a monitoring device that monitors a state of a driver becomesabnormal.

A driving assistance device according to the present invention includes:a plurality of monitoring devices that are provided for a vehicle andconfigured to monitor a state of a driver; a device examination unitconfigured to examine whether the monitoring devices are normal orabnormal; and an assistance degree determination unit configured todetermine a degree of possible assistance of driving assistance functionthat assists a driving operation of the driver on a basis of anexamination result from the device examination unit.

According to the present invention, the device examination unit examineswhether the monitoring devices that monitor the state of the driver arenormal or abnormal. On the basis of the examination result, theassistance degree determination unit determines the degree of thepossible assistance of the driving assistance functions. Therefore, thedriving assistance by the vehicle for the driver is cancelled lesseasily so that the merchantability of the vehicle can be improved.

In this case, it is preferable that the monitoring devices configured tomonitor the state of the driver include a driver camera configured tophotograph the driver, and a touch sensor that is provided for asteering part operated by the driver.

The state of the driver can be accurately monitored by the driver camerathat photographs the driver and the touch sensor that is provided forthe steering part to be gripped and operated by the driver.

The driving assistance functions may include an automated drivingfunction that automatically controls steering and acceleration anddeceleration of the vehicle, and the assistance degree determinationunit may be configured to determine that the automated driving functioncan be used when the device examination unit determines that both thedriver camera and the touch sensor are normal.

If both the driver camera and the touch sensor are normal, the automateddriving function that automatically controls the steering and theacceleration and deceleration of the vehicle can be used. Therefore, theautomated driving function can be performed in a state where a desireddriver's state detection function is secured.

On the other hand, the driving assistance function may include at leastone of a lane keeping function and a low speed following automatedtraveling function, and the assistance degree determination unit may beconfigured to determine that at least one of the lane keeping functionand the low speed following automated traveling function can be usedwhen the device examination unit determines that at least the touchsensor is normal.

If at least the touch sensor is normal, the lane keeping function or thelow speed following automated traveling function can be used. Therefore,even if the driver camera is abnormal, for example, the lane keepingfunction or the low speed following automated traveling function can beperformed, whose desired driver's state detection function is notaffected.

Note that if the driving assistance functions include an inter-vehicledistance control function that controls an inter-vehicle distance from apreceding vehicle, the assistance degree determination unit may beconfigured to determine that the inter-vehicle distance control functioncan be used even when the device examination unit determines that one ofor both the driver camera and the touch sensor are abnormal.

Even if it is determined that one of or both the driver camera and thetouch sensor are abnormal, the inter-vehicle distance control functionthat can operate without depending on a driver's state detection resultcan be used.

Therefore, the convenience can be improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram that illustrates a schematic structure of avehicle including a driving assistance device according to anembodiment;

FIG. 2 is a schematic diagram that illustrates a structure of a driverstate monitoring unit that monitors a state of a driver in the vehicle;

FIG. 3 is an examination/monitoring result determination table of adriver camera that is stored in a storage device of a device examinationECU of the vehicle;

FIG. 4 is an equivalent circuit diagram of the driver (human body) and atouch sensor that is connected to the device examination ECU;

FIG. 5 is an examination/monitoring result determination table of thetouch sensor that is stored in the storage device of the deviceexamination ECU of the vehicle;

FIG. 6 is a flowchart that is used for describing an operation of thevehicle including the driving assistance device according to theembodiment; and

FIGS. 7A, 7B, and 7C are transition explanatory views showing whetherdriving assistance functions can be used.

DESCRIPTION OF EMBODIMENT

Detailed description is hereinafter given concerning a preferredembodiment in a relation between a driving assistance device accordingto the present invention and a vehicle that includes the drivingassistance device with reference to the attached drawings.

[Structure]

FIG. 1 is a block diagram that illustrates a schematic structure of avehicle (also referred to as an own vehicle) 10 including a drivingassistance device 11 according to an embodiment.

The driving assistance device 11 basically includes a driver statemonitoring unit 12 and a travel control ECU 32.

FIG. 2 is a schematic diagram that illustrates a structure of the driverstate monitoring unit 12 that monitors the state of a driver H in thevehicle 10.

The driving assistance functions by the vehicle 10 include, for example,an inter-vehicle distance control function (ACC function), a lanekeeping function (LKAS function or LKS function), an automated lanechange function (ALC function), and the like that are performed bycombining an automated acceleration and deceleration operation, anautomated braking operation, and an automated steering operation. Thevehicle 10 having these driving assistance functions is configured sothat the driving assistance functions can operate while the driver statemonitoring unit 12 determines that the state of the driver H is normal,that is, the driver H is in what is called the driver-in-the-loop state(where the driver monitors the periphery).

As illustrated in FIG. 2, the driver state monitoring unit 12 includes,as monitoring devices for monitoring the state of the driver H, a drivercamera (driver photographing device) 14 provided between an upper partof a rearview mirror (not shown) and a roof, and a touch sensor (contactsensor) 18 provided for a steering wheel 16. Note that the driver camera14 may be provided in a dashboard.

The driver state monitoring unit 12 includes a monitoring resultdetermination ECU 20 (monitoring result determination electronic controlunit) as a monitoring result determination unit for the state of thedriver H, and a device examination ECU (device examination electroniccontrol unit) 21 that examines whether each monitoring device of thedriver camera 14 and the touch sensor 18 operates normally (whether eachmonitoring device is abnormal).

Note that an ECU (electronic control unit) is a computer including amicrocomputer, and includes a CPU, a ROM (including EEPROM), and a RAM,and moreover an input/output device such as an A/D converter and a D/Aconverter, a timer as a clocking unit, and the like. The ECU functionsas various function achieving units such as a controller, a calculationunit, a processing unit, and the like when the CPU reads out programsrecorded in the ROM and executes the programs. The function achievingunit can be formed by hardware (function achiever).

The monitoring result determination ECU 20 and the device examinationECU 21 may be combined into one ECU.

As illustrated in FIG. 1, the vehicle 10 includes, in addition to thedriver state monitoring unit 12, a peripheral information acquisitionunit 22, a vehicle information acquisition unit 24, a navigation device26, a driving unit 28 (an acceleration and deceleration device 62, abraking device 64, and a steering device 66), a notification device 30(a display device 68 and a speaker 70), and the travel control ECU(travel control electronic control unit) 32.

In this embodiment, the travel control ECU 32 includes an adaptivecruise control controller (ACC controller) 34 that plays a role of theinter-vehicle distance control function (ACC function), a lane keepingsystem controller (LKAS controller) 36 that plays a role of the lanekeeping function (LKAS function), and an automated lane changecontroller (ALC controller) 38 that plays a role of the automated lanechange function (ALC function) corresponding to controllers that controlthe plurality of driving assistance functions.

The travel control ECU 32 includes, in addition to the ACC controller34, the LKAS controller 36, and the ALC controller 38, an assistancedegree determination unit (function use possible/impossibledetermination unit) 40, and a notification controller 42. The assistancedegree determination unit 40 determines the degree of possibleassistance by these automated assistance functions (usable or not) onthe basis of an examination result from the device examination ECU 21.

Note that, as it has been commonly known, the inter-vehicle distancecontrol function (ACC function) is a function to enable travel while aconstant inter-vehicle distance from a preceding vehicle is kept (tocontrol inter-vehicle distance from the preceding vehicle), and the lanekeeping function (LKAS function) is a function to recognize a travellane of the own vehicle 10 and to maintain the traveling in the travellane. If the own vehicle 10 traveling in a road including a plurality oftraffic lanes will change the traffic lane, the automated lane changefunction (ALC function) is operated in a predetermined period after adirection indicator is turned on. If it is determined that there is novehicle around the own vehicle 10, the automated lane change functioncauses the own vehicle 10 to change the lane within a predeterminedperiod through the automated steering operation.

The peripheral information acquisition unit 22 includes a plurality ofcameras 72 and a plurality of radars 74 that obtain peripheralinformation around the vehicle 10 required for performing theinter-vehicle distance control function, the lane keeping function, andthe automated lane change function, for example. The camera 72(periphery capture device) is, for example, a solid-state cameraincluding a solid-state imaging element, such as a CCD camera or a CMOScamera (this camera may be an infrared camera). The camera 72 captures aperipheral image (real image) around the vehicle 10 including at leastan area ahead of the vehicle 10 when viewed from the vehicle 10, andoutputs an image signal corresponding to the peripheral image to thetravel control ECU 32.

Here, the peripheral image around the vehicle 10 includes, in additionto a lane mark image that forms the lane (traffic lane) on a travelingroad, another vehicle (obstacle) image and the like.

Note that the cameras 72 include, for example, a front photographingcamera, a side photographing camera, and a rear photographing camera.

The radar 74 outputs transmission waves corresponding to electromagneticwaves (here, millimeter waves) to the outside including at least thearea ahead of the vehicle 10 when viewed from the vehicle 10, andreceives reflection waves of the transmission waves that have reflectedfrom a detected object (for example, object such as another vehicle or apedestrian). Then, a reflection signal (also referred to as a radarsignal) corresponding to the reflection waves is output to the travelcontrol ECU 32.

Note that the radars 74 include, for example, a front detection radar, aside detection radar, and a rear detection radar.

The reflection signal detected by the radar 74 includes, for example,obstacle information (direction information, distance information,relative speed information) of the obstacle such as another vehicle whenviewed from the own vehicle 10.

The vehicle information acquisition unit 24 includes various sensors andvarious devices in order to acquire, in addition to informationregarding whether the automated driving execution is necessary, vehicleoperation information required for performing the inter-vehicle distancecontrol function, the lane keeping function, and the automated lanechange function, for example. Specifically, the vehicle informationacquisition unit 24 includes an automated driving switch 77 as anautomated driving indicator by which the driver H instructs whether thevehicle 10 performs the automated driving and a vehicle speed sensor 76that detects the vehicle speed of the vehicle 10, and moreover, anacceleration sensor, a yaw rate sensor, a steering angle sensor, and thelike that are not shown. Each sensor and each device output the acquiredvehicle information to the travel control ECU 32.

The navigation device 26 detects a current position of the vehicle 10using a satellite positioning device such as a GPS device, and shows auser (vehicle occupant) such as the driver H a route to a destination.In addition, the navigation device 26 includes a map information storageunit 44 that stores map information. The navigation device 26 detectsthe current position of the vehicle 10 on the basis of positioninformation from the GPS satellite and the map information stored in themap information storage unit 44.

From the viewpoint of detecting the current position of the vehicle 10,the navigation device 26 can be regarded as another vehicle informationacquisition unit 24. Moreover, the navigation device 26 can also beregarded as another peripheral information acquisition unit 22 thatdetects peripheral circumstance information corresponding to informationregarding a peripheral circumstance around the vehicle 10, such as roadtraffic regulations or road restrictions around the current position ofthe vehicle 10.

Note that FIG. 1 shows a type in which the navigation device 26 isattached to the vehicle 10; however, the structure is not limited tothis example. A portable information terminal such as a smartphone thatperforms intercommunication with the travel control ECU 32 can be usedas the navigation device 26. Moreover, the map information may be storedin an external server (not shown) and provided for the navigation device26 as necessary.

The driver camera 14 included in the driver state monitoring unit 12captures an image of an upper half body including a head of the driverH, and outputs an image signal Si to the monitoring result determinationECU 20 and the device examination ECU 21. The driver camera 14 ispreferably an infrared camera.

[Examination Method for Driver Camera 14]

FIG. 3 shows an examination result determination table 79 for the drivercamera 14 that is stored by the device examination ECU 21 in a storagedevice, and a monitoring result determination table 80 for the drivercamera 14 that is stored by the monitoring result determination ECU 20in the storage device.

The device examination ECU 21 determines the examination result of thedriver camera 14 on the basis of the image signal Si output from thedriver camera 14 with reference to the examination result determinationtable 79.

With reference to this examination result determination table 79, thedevice examination ECU 21 examines whether the driver camera 14 isnormal or abnormal on the basis of whether the image signal Si existsand a level (luminance distribution: including histogram) of the imagesignal Si.

The device examination ECU 21 examines and determines that the drivercamera 14 is abnormal (is not normal) when the image signal Si is notreceived (no image signal Si) due to the disconnection of a signal lineor the like, or when the level of the image signal Si is so high andsaturated or is so low and insufficient even if the image signal Si isreceived, that is, even if the image signal Si exists (the image signalSi is present).

Note that, for example, while intense light directly enters the drivercamera 14 through a lens, the level of the image signal Si may become sohigh and saturated. In addition, for example, if the lens of the drivercamera 14 is dirty, underexposure may occur and the level of the imagesignal Si may become low.

As shown in the examination result determination table 79, when thelevel of the image signal Si is within a predetermined range, the deviceexamination ECU 21 examines and determines that the driver camera 14 isnormal (the monitoring device is normal and is not abnormal).

If the device examination ECU 21 examines and determines that the drivercamera 14 is normal with reference to the monitoring resultdetermination table 80, the monitoring result determination ECU 20 thatmonitors the state of the driver H analyzes, for example, a facedirection and an open/closed state of eyelids of the driver H from animage obtained by the image signal Si. If the analysis result indicatesthat the face direction of the driver H is a looking aside direction(including a dozing state in which the eyelids are closed for a longtime) so that it is determined that the automated driving should not becontinued, the monitoring result determination ECU 20 determines thatthe result of monitoring the driver's state by the driver camera 14 is“not suitable” for performing the driving assistance function. Inaddition, if the driver H opens his eyelids and his face facessubstantially ahead so that it is determined that the automated drivingmay be continued, the monitoring result determination ECU 20 determinesthat the result of monitoring the driver's state by the driver camera 14is “suitable” for performing the driving assistance function.

Note that if it is determined that the examination result of the drivercamera 14 is abnormal, the monitoring result determination ECU 20determines that the monitoring result from the driver camera 14 is “notsuitable”.

The examination result as to whether the driver camera 14 is normal orabnormal is supplied from the device examination ECU 21 to theassistance degree determination unit 40 of the travel control ECU 32.

The monitoring result by the driver camera 14 as to whether the state ofthe driver H is suitable or not suitable is supplied from the monitoringresult determination ECU 20 to the travel control ECU 32.

[Examination Method for Touch Sensor 18]

As illustrated in FIG. 2, the steering wheel 16 of the vehicle 10includes a rim part 46 in an annular shape that is gripped by the driverH, and a connection part 50 that connects between an inner side of therim part 46 in a radial direction and a steering shaft 48. The touchsensor 18 is formed at the rim part 46.

The rim part 46 has a layer structure and includes a core metal made ofa metal material, a frame layer made of a resin material, a shieldlayer, and a sensor layer made of a conductive material that are notshown in this order from a central part to an outer side in the radialdirection.

FIG. 4 is an equivalent circuit diagram of the driver H (human body) andthe touch sensor 18 that is connected to the device examination ECU 21.

The touch sensor 18 of the driver state monitoring unit 12 includes anoscillator 19, and detects whether the driver H grips the steering wheel16 by his hands on the basis of change of a frequency (oscillationfrequency) f of the oscillator 19.

The touch sensor 18 outputs a touch signal (contact signal) St {alsoreferred to as St(f)} corresponding to a detection signal having thefrequency f to the monitoring result determination ECU 20 and the deviceexamination ECU 21.

FIG. 5 shows an examination result determination table 81 for the touchsensor 18 that is stored by the device examination ECU 21 in the storagedevice, and a monitoring result determination table 82 for the touchsensor 18 that is stored by the monitoring result determination ECU 20in the storage device.

The device examination ECU 21 measures the frequency f of the touchsignal St using a frequency counter (not shown), and determines theexamination result of the touch sensor 18 on the basis of the measuredfrequency f with reference to the examination result determination table81.

Here, description is given concerning a correspondence relation betweenthe value of the frequency (oscillation frequency) f of the touch signalSt of the touch sensor 18, and whether the driver H grips or does notgrip the steering wheel 16 (touch sensor 18) by his hands.

The frequency f based on an electrostatic capacitance C in a case wherethe driver H (human body) is not in contact with (does not grip) thesensor layer (to which oscillator 19 is connected) of the steering wheel16 (touch sensor 18) (this electrostatic capacitance C is referred to asnon-contact electrostatic capacitance Cnt) is referred to as anon-contact frequency fnt. The non-contact frequency fnt is expressed bythe following expression (1):fnt=½π(L×Cnt)^(1/2)  (1)where L is an inductance value of a coil that is connected to theoscillator 19.

The electrostatic capacitance C in a case where the driver H is incontact with (grips) the sensor layer of the steering wheel 16 (touchsensor 18) is a value that is obtained by adding an electrostaticcapacitance Ch of the driver H to the non-contact electrostaticcapacitance Cnt.

Thus, the frequency f (referred to as contact frequency ft) based on theelectrostatic capacitance C (referred to as contact electrostaticcapacitance Ct, Ct=Cnt+Ch) in the case where the driver H (human body)is in contact with (grips) the sensor layer of the steering wheel 16(touch sensor 18) is expressed by the following expression (2):ft=½π{(L×(Cnt+Ch)}^(1/2)  (2)

In consideration of the expression (1) and the expression (2), it isunderstood that the contact frequency ft in the case where the driver H(human body) grips the steering wheel 16 (touch sensor 18) is lower thanthe non-contact frequency fnt in the non-gripping case (in the casewhere the driver H does not grip the steering wheel). That is to say, arelation of ft<fnt is satisfied.

Note that each of L, Cnt, and Ch varies; thus, even if this variationcauses a variation in the frequency f, for example, Cnt is set to belower than Ch (Cnt<Ch) so that the relation of ft<fnt is satisfied. Thatis to say, as the touch sensor 18, an electrostatic capacitance sensorthat can detect whether the driver H grips the steering wheel 16 (touchsensor 18) by his hands on the basis of the oscillation frequency f ofthe oscillator 19 is used.

Moreover, when two vehicle occupants grip the steering wheel 16 (touchsensor 18), the contact electrostatic capacitance Ct increasesabnormally (substantially, Ct=Cnt+2×Ch). In this case, the frequency fbecomes an abnormal frequency (abnormal low frequency) fab that is lowerthan the normal contact frequency ft (see examination resultdetermination table 81). That is to say, a relation of fab<ft issatisfied.

Furthermore, if the touch sensor 18 itself is broken, the frequency fbecomes zero value or an abnormal frequency (abnormal high frequency)fab that is higher than the non-contact frequency fnt.

As above, description has been given concerning the correspondencerelation between the value of the frequency (oscillation frequency) f ofthe touch signal St of the touch sensor 18, and whether the driver Hgrips or does not grip the steering wheel 16 (touch sensor 18) by hishands.

With reference to the examination result determination table 81, thedevice examination ECU 21 determines the examination result of the touchsensor 18 on the basis of whether the touch signal St exists and thefrequency f when the touch signal St exists.

If the touch signal St is not received due to the disconnection of thesignal line or the like (no touch signal St), or if the frequency f isthe abnormal frequency fab even when the touch signal St is received,the device examination ECU 21 examines and determines that the touchsensor 18 is abnormal (monitoring device is broken).

If the frequency f of the touch signal St is the contact frequency ft orthe non-contact frequency fnt, the device examination ECU 21 examinesand determines that the touch sensor 18 is normal (monitoring device isnormal).

If the device examination ECU 21 determines that the frequency f is thecontact frequency ft, the monitoring result determination ECU 20 thatmonitors the state of the driver H determines that the monitoring resultof the state of the driver H is preferable to continue the automateddriving and is “suitable” for performing the driving assistance functionwith reference to the monitoring result determination table 82.

In addition, if the device examination ECU 21 determines that thefrequency f is the non-contact frequency fnt or the abnormal frequencyfab, the monitoring result determination ECU 20 determines that themonitoring result of the state of the driver H is not preferable tocontinue the automated driving and is “not suitable” for performing thedriving assistance function.

The examination result as to whether the touch sensor 18 is normal orabnormal is supplied from the device examination ECU 21 to theassistance degree determination unit 40 of the travel control ECU 32.

The monitoring result as to whether the state of the driver H issuitable or not suitable by the frequency f of the touch sensor 18 issupplied from the monitoring result determination ECU 20 to the travelcontrol ECU 32.

Note that the steering wheel 16 is not limited to a steering part in anannular shape as shown in FIG. 2, and may be replaced by, for example, abutterfly type, a joystick, a button, or the like.

Referring back to FIG. 1, the driving unit 28 includes the accelerationand deceleration device 62, the braking device 64, and the steeringdevice 66.

The acceleration and deceleration device 62 includes an acceleration anddeceleration ECU (acceleration and deceleration electronic control unit)(not shown) and a driving source of the vehicle 10, such as an engine(not shown) or a driving motor (not shown) whose operation is controlledby the acceleration and deceleration ECU.

The braking device 64 includes a brake ECU (brake electronic controlunit) that is not shown and a brake actuator (not shown) whose operationis controlled by the brake ECU.

The steering device 66 includes an electric power steering ECU (electricpower steering electronic control unit, hereinafter referred to asEPSECU) and an electric power steering device (hereinafter referred toas EPS) that are not shown.

The acceleration and deceleration device 62, the braking device 64, andthe steering device 66 of the driving unit 28 operate based on thedetermination by the assistance degree determination unit 40 of thetravel control ECU 32 in accordance with control instructions outputfrom the ACC controller 34, the LKAS controller 36, and the ALCcontroller 38.

Note that the acceleration and deceleration device 62, the brakingdevice 64, and the steering device 66 operate also in accordance with anoperation of an accelerator pedal (not shown), an operation of a brakepedal (not shown), and an operation of the steering wheel 16 by thedriver H, respectively.

The notification device 30 includes the display device 68, the speaker70, and a notification ECU (notification electronic control unit) (notshown). In accordance with a notification instruction output from thetravel control ECU 32, the notification ECU operates the display device68 and the speaker 70. The display device 68 performs display regardingthe automated driving, for example. The display device 68 may constitutea part of a meter of an instrument panel that is not shown, for example.The display device 68 may also serve as a display unit of the navigationdevice 26.

The ACC controller 34, the LKAS controller 36, and the ALC controller 38independently or collaboratively perform control required for the travelof the vehicle 10 by the automated driving. For example, the ACCcontroller 34 outputs to the accelerator and decelerator ECU of thedriving unit 28, an operation signal that relates to traveling followinga preceding vehicle of the own vehicle 10 while keeping a predeterminedinter-vehicle distance from the preceding vehicle; the LKAS controller36 outputs to the EPSECU of the driving unit 28, an operation signalthat prevents the vehicle 10 from going out of the traveling lane; andthe ALC controller 38 outputs to the accelerator and decelerator ECU andthe EPSECU of the driving unit 28, an operation signal that automatedlyguides the own vehicle 10 from a current traveling lane (lane beforechanging lane) to a target lane.

Here, for example, the ALC controller 38 generates lane changeinformation including a lane change trajectory on the basis of thevehicle information that indicates the state of the vehicle 10 obtainedby the vehicle information acquisition unit 24, information that isobtained based on the vehicle information, and the information regardingthe peripheral circumstance of the vehicle 10 obtained by the peripheralinformation acquisition unit 22. Then, the ALC controller 38 controlsthe acceleration and deceleration device 62, the braking device 64, andthe steering device 66 so as to perform the automated lane changecontrol of the vehicle 10 on the basis of the generated lane changeinformation.

[Operation]

Next, with reference to a flowchart in FIG. 6, description is givenconcerning the relation between a switching operation for the divingassistance function of the vehicle 10 by the driving assistance device11 according to the embodiment that is basically configured as describedabove and whether there is an abnormality in the driver camera 14 andthe touch sensor 18 (abnormal or normal).

Note that it is the travel control ECU 32 and the function usepossible/impossible determination unit 40 that execute the programsaccording to the flowchart. Since it is complicated to describe theexecution subject in each process, the execution subject is described ifnecessary. To help understanding and avoid the complication, themonitoring result of the driver's state by the monitoring resultdetermination ECU 20 on the basis of the image signal Si from the drivercamera 14 and the touch signal St from the touch sensor 18 is basically“suitable” for performing the driving assistance function.

In step S1, the travel control ECU 32 determines whether the vehicle 10is in the automated driving (the automated driving switch 77 is on andthe vehicle 10 is traveling) (step S1: YES), or the vehicle 10 isstarting the automated driving, that is, in a transition from an OFFstate to an ON state of the automated driving switch 77 (step S1: YES),or the vehicle 10 is in the other cases (for example, the automateddriving switch 77 is in the OFF state and the vehicle 10 is traveling)(step S1: NO). If the determination in step S1 is negative (step S1:NO), after a predetermined time, the process returns to thedetermination process in step S1 and the process is continued.

If it is determined that the vehicle 10 is in the automated driving oris starting the automated driving (step S1: YES), the assistance degreedetermination unit 40 acquires from the device examination ECU 21, theexamination result as to whether the driver camera 14 is normal orabnormal, and the examination result as to whether the touch sensor 18is normal or abnormal in step S2.

In step S2, in a case where, on the basis of the acquired examinationresult, it is recognized that both the driver camera 14 and the touchsensor 18 are normal (step S2: YES), if the monitoring result of thestate of the driver H by the monitoring result determination ECU 20using the driver camera 14 and the touch sensor 18 is “suitable”, theassistance degree determination unit 40 determines that all the drivingassistance functions, that is, the inter-vehicle distance controlfunction, the lane keeping function, and the automated lane changefunction can be used. Then, in step S3, the automated driving by thecontrols using the ACC controller 34, the LKAS controller 36, and theALC controller 38 of the travel control ECU 32 is allowed.

In step S3, if the vehicle 10 is in the automated driving, the travelcontrol ECU 32 continues the automated driving (ACC function+LKASfunction+ALC function), and if the vehicle 10 is starting the automateddriving, an operation of the automated driving is started. After that,the process of and after step S1 is repeated.

As shown in transition explanatory views of the driving assistancefunctions in FIG. 7A, the automated driving (ACC function+LKASfunction+ALC function) is performed in a case that both the detection ofthe face direction or the like of the driver H by the driver camera 14and the gripping detection by the touch sensor 18 are functioning.

If the determination in step S2 is negative (step S2: NO), theassistance degree determination unit 40 determines whether the drivercamera 14 is abnormal and the touch sensor 18 is normal in step S4.

Note that cases in which the determination in step S2 is negative arethe following cases: (driver camera 14: abnormal, touch sensor 18:normal); (driver camera 14: normal, touch sensor 18: abnormal); and(driver camera 14: abnormal, touch sensor 18: abnormal).

In the determination in step S4, if the driver camera 14 is abnormal andthe touch sensor 18 is normal (step S4: YES), the notificationinstruction indicating the determination result in step S4 istransmitted to the notification device 30 through the notificationcontroller 42 in step S5.

Accordingly, the notification device 30 causes the display device 68 andthe speaker 70 to notify that: the driver camera 14 is abnormal; and thedriving assistance function makes a transition to or starts not theautomated driving (ACC function+LKAS function+ALC function) but anassistance driving (ACC function+LKAS function) in which a low speedfollowing automated traveling function {(also referred to as TJA:Traffic Jam Assist function) or the like can be performed.

Next, if it is recognized that the driver camera 14 is abnormal and thetouch sensor 18 is normal (step S4: YES) from the acquired examinationresult, the assistance degree determination unit 40 determines that theinter-vehicle distance control function and the lane keeping functioncan be used and the assistance driving (ACC function+LKAS function) bythe controls using the ACC controller 34 and the LKAS controller 36 ofthe travel control ECU 32 is allowed in step S6.

As shown in transition explanatory views of the driving assistancefunctions in FIG. 7B, the assistance driving (ACC function+LKASfunction) can be performed in a case that the gripping detection by thetouch sensor 18 is functioning even if the driver camera 14 does notfunction.

If the determination in step S4 is negative (step S4: NO), that is,(driver camera 14: normal, touch sensor 18: abnormal) or (driver camera14: abnormal, touch sensor 18: abnormal), the notification instructionindicating the determination result in step S4 is transmitted to thenotification device 30 through the notification controller 42 in stepS7.

Accordingly, the notification device 30 issues notification of thedetermination result in step S4 (state of monitoring device) by displayand voice, and causes the display device 68 and the speaker 70 to notifythat the vehicle 10 makes a transition from the automated driving (ACCfunction+LKAS function+ALC function) or the assistance driving (ACCfunction+LKAS function) to only the ACC function, or starts theoperation with only the ACC function.

As shown in transition explanatory views of the driving assistancefunction in FIG. 7C, the assistance driving (ACC function) can beperformed using the cameras 72 and the radars 74 of the peripheralinformation acquisition unit 22 even if the driver camera 14 and thetouch sensor 18 do not function.

SUMMARY OF EMBODIMENT

As described above, the driving assistance device 11 according to thisembodiment includes: the plurality of monitoring devices, such as thedriver camera 14 and the touch sensor 18, that is provided for thevehicle 10 and configured to monitor the state of the driver H; thedevice examination ECU 21 configured to examine whether the monitoringdevices are normal or abnormal; and the assistance degree determinationunit (function use possible/impossible determination unit) 40 configuredto determine the degree of the possible assistance of the drivingassistance functions (usable or not, its kind) on the basis of theexamination result from the device examination ECU 21.

In this manner, the device examination ECU 21 examines whether themonitoring devices that monitor the state of the driver H are normal orabnormal. On the basis of the examination result, the assistance degreedetermination unit (function use possible/impossible determination unit)40 determines the degree of the possible assistance of the drivingassistance functions (usable or not). Therefore, the driving assistanceby the vehicle 10 for the driver H is cancelled less easily.

Note that the state of the driver H can be accurately monitored by thedriver camera 14 that photographs the driver H and the touch sensor 18that is provided for the steering wheel 16 which is gripped and operatedby the driver H.

Then, the assistance degree determination unit (function usepossible/impossible determination unit) 40 is configured to determinethat all the driving assistance functions of the inter-vehicle distancecontrol function, the lane keeping function, and the automated lanechange function can be used when the device examination ECU 21determines that both the driver camera 14 and the touch sensor 18 arenormal (step S2: YES). In this case, the automated driving function inwhich the acceleration and deceleration operation, the steeringoperation, and the braking operation by the driver H are not requiredcan be performed in a state where a desired driver's state detectionfunction is secured.

Moreover, the assistance degree determination unit (function usepossible/impossible determination unit) 40 is configured to determinethat at least one of the lane keeping function and the low speedfollowing automated traveling function (inter-vehicle distance controlfunction+lane keeping function) can be used (step S4: YES) when thedevice examination ECU 21 determines that the driver camera 14 isabnormal and the touch sensor 18 is normal.

Accordingly, if at least the touch sensor 18 is normal, the lane keepingfunction or the low speed following automated traveling function can beused. Therefore, even if the driver camera is abnormal, for example, thelane keeping function or the low speed following automated travelingfunction can be performed, whose desired driver's state detectionfunction is not affected.

Note that the assistance degree determination unit (function usepossible/impossible determination unit) 40 is configured to determinethat the inter-vehicle distance control function that can operatewithout depending on a driver's state detection result can be used evenwhen the device examination ECU 21 determines that one of or both thedriver camera 14 and the touch sensor 18 are abnormal. Therefore, theconvenience can be improved.

The vehicle 10 according to the present invention is not limited to theembodiment above, and can employ various structures without departingfrom the gist of the present invention. For example, instead of thetouch sensor 18 that is the electrostatic capacitance type, a pressuresensor may be used.

The invention claimed is:
 1. A driving assistance device comprising: aplurality of monitoring devices that are provided for a vehicle andconfigured to monitor a state of a driver, and include a driver cameraconfigured to photograph the driver, and a touch sensor that is providedfor a steering part operated by the driver; a device examination unitconfigured to examine whether the monitoring devices are normal orabnormal; and an assistance usability determination unit configured todetermine whether a driving assistance function is usable on a basis ofan examination result from the device examination unit, the drivingassistance function including automated driving functions automaticallycontrols an inter-vehicle distance control function, a lane keepingfunction and an automated lane change function, wherein theinter-vehicle distance control function controls an inter-vehicledistance from a preceding vehicle in a lane in which the vehicle istraveling, the lane keeping function recognizes the lane in which thevehicle is traveling and controls the vehicle to keep traveling in thelane without going out of the lane, the automated lane change functionautomatically controls steering of the vehicle to change lanes within apredetermined period of time from the lane in which the vehicle istraveling to another lane, the assistance usability determination unitis configured to determine that all the inter-vehicle distance controlfunction, the lane keeping function and the automated lane changefunction can be used if both the driver camera and the touch sensor arenormal, the assistance usability determination unit is configured tosuspend the automated lane change function if the driver camera isabnormal, the assistance usability determination unit is configured tosuspend the lane keeping function and the automated lane change functionif the touch sensor is abnormal, and the assistance usabilitydetermination unit is configured to determine that the inter-vehicledistance control function can be used even when the driver camera andthe touch sensor are abnormal.
 2. The driving assistance deviceaccording to claim 1, wherein: the driving assistance function includesa low speed following automated traveling function; and the assistanceusability determination unit is configured to determine that at leastone of the lane keeping function and the low speed following automatedtraveling function can be used when the device examination unitdetermines that at least the touch sensor is normal.